HF signals receiving circuitry for e.g. cable TV - uses variable capacitance diodes for tuning to VHF and UHF bands and conversion to IF

摘要

In a circuit for reception of HF signals of the VHF and UHF bands, and for conversion of these to an IF signal, using variable capacitance diode timers, the diodes are used for both bands. The diodes have a starting capacitance of between 38 pF to 40 pF, and an end capacitance of between 2.35 pf to 2.55 pF. as well as a series resistance of 0.7 ohms to 0.08 ohms . Pref. the reception zone is split into three adjoining bands, are from 45 to 130 Megahertz, the second from 135 to 410 Megahertz and the third from 418 to 860 Megahertz. ADAVNTAGE - Inexpensive diodes cover while reception field.